January 11, 2006
Reuters
MSNBC

LONDON - An infectious fungus aggravated by warmer global temperatures has killed entire populations of frogs in Central and South America and driven some species to extinction, scientists said on Wednesday.

Photo: This Panamanian golden frog is one of the 110 or so species of harlequin frogs, many of which are being wiped out by a fungus. (Forrest Brem)

In research that showed the effects of rising temperatures on delicate ecosystems, a team of researchers found that a warming atmosphere encouraged the spread of a fungus that has wiped out species of harlequin frogs and golden toads.

“This is the first clear evidence that widespread extinction is taking place because of global warming,” Alan Pounds, an ecologist of the Monteverde Cloud Forest Preserve in Costa Rica, said in an interview. “Climate change is already altering the dynamics of infectious disease and causing species to disappear.”

In a study published in the journal Nature, Pounds and his team determined the link by analyzing sea surface and air temperatures, which rose by 0.18 degrees Centigrade per decade between 1975 and 2000.

FUNGUS TIED TO CLOUDS

Warmer temperatures increased cloud cover over the tropical mountain which the scientists believe promoted conditions to spur the growth of the chytrid fungus that kills frogs.

“There is absolutely a linkage between global warming and this disease — they go hand-in-hand,” said Arturo Sanchez-Azofeifa, a University of Alberta scientist and a co-author of the research.

“With this increase in temperature, the bacteria has been able to increase its niche and wipe out large populations of amphibians in the Americas,” he added in a statement.

Photo: A Central American harlequin frog (Robert Puschendorf)

About a third of the 5,743 known species of frogs, toads and other amphibians are classified as threatened, according to the Global Amphibian Assessment.

Up to 167 species may already be extinct and another 113 species have not been found in recent years. Habitat loss is the greatest threat to amphibians but fungal disease is also a serious problem.

‘ALARM’ FOR HUMANS

Andrew Blaustein, an Oregon State University zoologist, and Andy Dobson, a Princeton University biologist, described the research as a breakthrough.

“The powerful synergy between pathogen transmission and climate change should give us cause for concern about human health in a warmer world,” they said in a commentary in Nature.

“The frogs are sending an alarm call to all concerned about the future of biodiversity and the need to protect the greatest of all open-access resources — the atmosphere,” they added.
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